Studying the Evolution of Complex Phenotypes

I study the evolution of complex morphological phenotypes. Although I have worked on a large number of aquatic organisms and phenotypes ranging from pectoral fin swimming in African Lake Malawi cichlids to anti-predator defenses in Central American snails, my research is largely concentrated on the feeding apparatus of fish. The jaws of fishes offer an ideal organismal phenotype for examining the forces that structure functional adaptation in a complex system. Humans that only have a few joints and muscles that readily move while we feed. In contrast, fish generally have over 30 muscle and skeletal elements that move in a coordinated fashion when they capture and breakdown a prey item.

By studying the mechanistic basis of fish feeding specialization, my research program is also able to circumvent the lack of replication that often plagues evolutionary studies of ecologically important historical phenomena. Determining why a particular species of fish might be specialized to eat snails or other fish is particularly difficult if it happened only once. However, because there are over 25,000 species of fish, particular feeding habits have often evolved repeatedly. Within the cichlid fishes for example, a huge number of historically independent and convergent trophic phenotypes have arisen through modifications of conserved musculoskeletal elements that comprise their highly kinetic skull. This replicated evolutionary framework within a single fish group provides the power to address broad questions concerning the mechanisms underlying the evolution of ecological novelty.

In both the field and in the lab, I have been involved with studies to determine performance capabilities in live organisms to test if phenotypes one can model as simple machines like levers or force-resisting structures exhibit mechanical tradeoffs in vivo. This approach allows the examination of the functional consequences of both predatory abilities and anti-predatory defenses to quantitatively elucidate the mechanistic properties of adaptations in predator-prey interactions. My work also integrates phylogenetic reconstruction and population genetics to provide evolutionary maps for understanding when and how traits arise. These evolutionary studies that lie at the interface of micro- and macroevolution provide a means to place phenotypic novelties that arise plastically and/or have a genetic basis within a comparative framework.

Currently, I am working to incorporate genomic tools such as gene expression and quantitative genetics into microevolutionary analyses of fish feeding. These exciting new techniques and technologies will allow us to ultimately understand what the developmental genetic changes are that occur within populations to produce functional novelties.